With the development of science and technology, people have gradually employed an electrophoresis display (EPD) or a portable computer system which is installed with a reading software to read E-books. Thus, people can carry various books more conveniently, and the problem of wasting paper can also be avoided.
However, when the portable computer system displays the contents of the E-books, the whole system operates in the power management mode S0 (i.e., in the normal operation), so that the computer system consumes most power. The so-called power management mode S0 is a power management standard defined in the Advanced Configuration and Power Interface (ACPI) protocol.
From the above description, it can be seen that the portable computer system must be charged after a user reads the E-books for several hours. And this is inconvenient in use.